Manual drums to power disc

Thanks Guys,

Turd

The calipers are already sorted.

I've read somewhere that the lever mechanism ratio in the pedal assembly is different going from manual to disc but there didn't seem to be a definitive answer. 

As BU1 said, don't forget the delay valve (or hold-off valve) for the rear brakes. On the AMX/Javelins, it is located on the right rear frame rail, just ahead of where the frame rail kicks up over the rear axle. I did the same disc conversion on a non Go-Pak drum brake 68 AMX, used a Matador single piston setup on front. I found a replacement delay or hold-off valve for a late 60's Camaro to be the same as the ones on my other GoPak AMX's. I think it came from The Right Stuff, but a Google search should find it. Ask for a disc brake hold-off valve, it actually holds off the application of pressure to the rear brakes until the fronts have applied. Keeps the rear end from getting squirrely until the disc brakes bite. The Camaro valve is identical to the one AMC used, down to the tab on the mounting bracket that fits in the hole next to the tapped hole for the mount bolt.

  You will also need a disc brake rear line set. With the addition of the hold-off valve, the plumbing is different than for a drum brake car. The disc brake line set is 2 pieces, the 2nd short piece goes from the hold-off valve to the hard point where the flex line attaches to the rear axle.

  While you're at it, now is a good time to clean/rebuild the brake distribution valve located on the firewall under the heater motor. It is not a proportioning valve, it just senses any imbalance between the front/rear brake systems and if working properly, will illuminate a red dash light if you have a serious loss of pressure on either system. Of course, if you have a serious loss of front or rear brake pressure, you'll probably know it before the red light alerts you to the problem, but hey, it was a Federal Safety Standard requirement.

  Good luck with the disc conversion, it's worth the effort.

Edit:

  Just re-read your post. If you have a 68 Javelin donor, the hold-off valve should be on the right rear frame rail. The only difference between the Jav and the AMX plumbing is the length of the main rear brake line, all else is the same.

Terry

Yes, you will need a proportioning valve, as the brake lines

from the MC have to be plumbed in together, front and rear.

Some install it in the "traditional spot," p/s of the firewall ('68-'70).

Others put it near the MC.  Whichever company you're using

for the disc brakes should be able to advise you on which pv

to purchase.